Power spectra (plotted as power × frequency) of all the sources, binned by mass and Eddington ratio. The variances were calculated for timescales of 30, 75, 150, and 300 days, and in this plot the corresponding frequencies, f = 1/t, were multiplied by (M/M₈)^0.5 to put them on a common x-axis scaled to the bend timescale approximately, as was measured by Burke et al. (2021). The colour represents the different bins in R_Edd. The solid black line represents a bending power law model with α_L = 0 and α_H = −2, similar to the DRW model, with a bend timescale of 200 days for a 10⁸ M_⊙ black hole. (We note that as power is multiplied by frequency in the plot, the part of the black line with α_L = 0 appears to rise with frequency.) Frequencies are in units of day⁻¹.